A. Field of Invention
The present invention is related to wireless communication systems, and more particularly, to a method and system of managing channel element licenses in a plurality of wireless base stations.
B. Description of Related Art
In a typical wireless communication system, an area is divided geographically into a number of cell sites, each defined by one or more radiation patterns created by an emission of radio frequency (RF) electromagnetic (EM) waves from a respective base transceiver station (BTS) antenna. Similarly, BTS antennae are configured for the reception of EM waves emanating from mobile devices. Each cell site is typically further divided into two, three, or more sectors, where the sectors provide transmit and receive radio coverage for a selected area within the cell site.
Associated with the BTS is a plurality of channel elements for processing individual signal channels. Specifically, in CDMA communication systems, individual communication channels are separable due to their use of channel-specific concatenated coding sequences. In the forward channel, a unique PN code (commonly referred to as a short PN code offset) is used to distinguish channels in a given sector from those in surrounding sectors and cells. Within each sector, channels are further distinguished by yet another code, termed a Walsh code. In an adjacent sector, the Walsh codes may be reused because channel separation is provided by a different offset of the short PN code for that sector. Thus, the number of available forward channels (BTS to MS) on a given carrier frequency in a sector is limited by the number of available Walsh codes. In the ANSI/TIA/EIA-95-B-99 standard entitled “Mobile Station-Base Station Compatibility Standard for Wideband Spread Spectrum Cellular Systems” (published Feb. 1, 1999), the contents of which are incorporated by reference herein, there are sixty-four available Walsh codes, while in CDMA 2000 series (TIA/EIA IS-2000 Series, Rev. A, published Mar. 1, 2000), one hundred twenty-eight Walsh codes are available. Both of the ANSI/TIA/EIA-95-B-99 and the TIA/EIA IS-2000 Series, Rev. A, standards are incorporated herein by reference, and are available from the Telecommunication Industry Association, 2500 Wilson Boulevard, Suite 300, Arlington, Va. 22201.
On the reverse channel, from the mobile to the BTS, a slightly different code concatenation is used. The Walsh codes are used to identify a data symbol alphabet, the short PN code is used for synchronization purposes, and the long code PN code is used to identify the individual mobile channel.
The signal processing on the forward and reverse channels is performed in a channel element (CE) of the BTS. In existing systems, each BTS typically has a bank of CEs that are licensed and available for use on a static basis. Therefore, one disadvantage of existing BTS license schemes is that each BTS must contain enough licensed CEs to carry all of the traffic during the busiest hour of the day. Because not all sites have the same busy hour, the existing license management techniques result in wasted resources, or over-allocation of network resources.
In other situations, existing schemes of CE licensing may be restricted such that CEs are licensed only in blocks of a predetermined size. Specifically, a typical base station channel element card may come with forty-eight physical CE's, of which half may be enabled by default, with the remaining twenty-four CE's being licensed (and thus enabled for use) only in groups of eight. This is inefficient due to the fact that a BTS which requires twenty-five CE's must be upgraded from twenty-four to thirty CE's, rather than just the required tweny-five.
Consequently, a CE licensing system that overcomes these and other limitations is desirable.